Two of the oldest volcanoes on Mars, which were erupting over three billion years ago, may still be active.

This startling conclusion is reached by geologists using new data from the Mars Global Surveyor spacecraft, currently orbiting the planet.

The combination of the heat and energy from the volcanoes and the liquid water makes conditions ripe for the evolution of life

Prof Tracey Gregg, University of Buffalo

The volcanoes, named Tyrrhena Patera and Hadriaca Patera, are located in the southern hemisphere of the Red Planet.

The volcanoes could once have melted ice, creating conditions capable of sustaining life, said Professor Tracy Gregg of the University of Buffalo, US.

"What's most intriguing about these volcanoes is that they are surrounded by channels," said Professor Gregg.

"Of all the volcanoes on Mars, these volcanoes have the largest and greatest numbers of channels associated with them, indicating that there was a lot of water around when they were forming, though there doesn't appear to be any around now."

Essential chemicals

Professor Gregg said that the channels might have formed because the volcanoes could have melted ice on the ground. The water would have flowed downhill, away from the volcano's centre, carving the channels.

"The combination of the heat and energy from the volcanoes and the liquid water makes conditions ripe for the evolution of life, at least as we understand it on Earth," said Professor Gregg.

She adds that volcanoes are also a source of many of the essential chemicals that may be necessary for the evolution of biological organisms.

Tyrrhena Patera in 3D and with an exaggerated vertical scale

The preliminary analysis by Professor Gregg and her colleagues is based on new data gathered by the Mars Orbiter Camera (Moc) and the Mars Orbiter Laser Altimeter (Mola), onboard the Mars Global Surveyor.

"The Moc is a very high-resolution camera that allows us to see features on Mars as small as one metre across, so we can start to see some really significant things, like individual boulders and piles of sediment, which is allowing us to really piece together Martian history," she said.

"There are areas on Earth we don't know that well, such as Antarctica and the entire ocean floor."

As more data pour in from this mission, Professor Gregg and her colleagues will try to learn more about how evidence of water on Mars may provide clues to questions about whether or not life has existed on the Red Planet.